any of various nonmuscular parts of the carcasses of beef and veal, mutton and lamb, and pork, which are either consumed directly as food or used in the production of other foods. Variety meats have been a part of the human diet since the invention of cooking, which rendered the otherwise indigestible animal parts edible. In nutritional terms, several variety meats are richer in certain vitamins, minerals, and forms of protein than muscle tissue; calf's liver, for example, is a major dietary source of iron, and sweetbread (thymus) is considerably higher in the water-soluble protein albumin than is beef.